1. Field of the Invention
The present invention relates to a heat pump, and more particularly, to a heat pump and a method for controlling a cooling/heating capability thereof, which can make an efficient control of a cooling/heating capability according to a cooling/heating condition of the heat pump.
2. Background of the Related Art
In general, the heat pump is an air conditioner in which heat absorption and dissipation of a refrigerant is used for cooling/heating a room, selectively. FIG. 1 illustrates a cooling operation of a related art heat pump, and FIG. 2 illustrates a heating operation of a related art heat pump schematically. The related art heat pump is provided with a compressor 1 for compressing the refrigerant, an indoor and an outdoor heat exchangers 4 and 3 installed inside of the room and outside of the room for condensing or evaporating the refrigerant, and capillary tube 5 between the heat exchangers. In general, according to an operation requirements, such as a room temperature and the like, in operation of the heat pump, a heating load required for a heating is greater by 1.4 times than a cooling load required for cooling. In order to adjust the cooling/heating capacity of the f heat pump, there are a change over valve 6 on the compressor 1, a flow cut-away valve 7 and a back pressure capillary tube 8 for controlling the change over valve 6.
A process for controlling a cooling capacity of the related art heat pump will be explained. The refrigerant compressed at the compressor 1 flows to the outdoor heat exchanger 3 through a four-way valve 2 and is condensed at the outdoor heat exchanger 3, expanded at the capillary tube 5, evaporated at the indoor heat exchanger 4, and flows to the compressor 1, again. On the same time with this, the flow cut-away valve 7 connected to an inlet to the compressor 1 is opened, a portion of the change-over valve on the compressor 1 connected to the flow cut-away valve 7 becomes to have a low pressure, while a portion of the change-over valve 6 in communication with the compressor 1 becomes to have a high pressure. Accordingly, a plunger (not shown) at an end of the change-over valve in communication with the compressor is pushed back by a pressure difference until the plunger is blocked by a stopper, to cause diffusion of the compressed refrigerant in the compressor 1 into an inlet 12, and the high pressure refrigerant flowing through the back pressure capillary tube 8 connected to an outlet 11 of the compressor 1 to flow to the inlet 12 through the flow cut-away valve 7. And, the refrigerant compressed at the compressor 1 flows to the indoor heat exchanger 4 following a flow path of the indoor heat exchanger 4 selected by the four way valve 2, is condensed at the indoor heat exchanger 4, expanded at the capillary tube 5, evaporated at the outdoor heat exchanger 3, and flows back to the compressor 1 again. During operation of the heat pump, the flow cut-away valve 7 is kept closed, to block flow of the high pressure refrigerant flowing to the back pressure capillary tube through the outlet 11 into the inlet 12 of the compressor 1. Accordingly, since a pressure of the refrigerant compressed at the compressor and passed through the back pressure capillary tube 8 is higher than a pressure of the refrigerant before being compressed in the compressor 1, the plunger 61 in the change-over valve 6 is drawn toward the compressor 1, to isolate the compressor 1 from the change-over valve 6. According to the foregoing process, a rate of refrigerant discharge from the compressor 1 is controlled for the cases of cooling/heating, and cooling/heating capability of the heat pump is varied.
However, the use of the flow cut away valve and the back pressure capillary tube in cooling, and the capillary tube in heating of the related art heat pump for varying the cooling/heating capability makes a system of the heat pump complicated, deteriorates a productivity, and pushes up a production cost. The leakage of the refrigerant through the back pressure capillary tube 8 during cooling drops the cooling capability, that reduces a system efficiency, unnecessarily.
Accordingly, the present invention is directed to a heat pump and a method for controlling operation thereof that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a heat pump and a method for controlling operation thereof, in which a discharge rate of the compressor is controlled for varying cooling/heating capability efficiently, to meet a required cooling/heating capability ratio.
Another object of the present invention is to provide a heat pump and a method for controlling operation thereof, in which a cooling/heating capability is varied efficiently, for improving a system efficiency.
Other object of the present invention is to provide a heat pump and a method for controlling operation thereof, which has a simple cooling/heating capability varying system for easy fabrication and reduction of a production cost. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the heat pump includes a compressor having an inlet for drawing, and compressing low temperature and low pressure refrigerant, and an outlet for discharging the compressed refrigerant, a four way valve for connecting the outlet and the inlet to an indoor heat exchanger and an outdoor heat exchanger selectively depending on cooling/heating, the indoor heat exchanger for evaporating/condensing the refrigerant by heat exchange with room air in cooling/heating respectively, the outdoor heat exchanger for evaporating/condensing the refrigerant by heat exchange with external air, a capillary tube having a reduced diameter for expansion of the refrigerant, a change over valve having a plunger movable by a pressure difference provided therein, and a connection tube connected the indoor heat exchanger and a four way valve, and a bypass tube connected between the connection tube and the change over valve.
The heat pump of the present invention controls a discharge of the compressor by using a bypass tube to increase a ratio of cooling/heating which is approx. 1.4 for prevention of reduction of a system efficiency.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.